We have two separate Dionex DX-500 ion chromatograph systems, both with conductivity detectors, autosamplers, and eluant generators. One is dedicated to cations and the other is dedicated to anions and silica. The instrument for anions and silica also has a spectrophotometer detector. These instruments are capable of analyzing many inorganic ions and some organic acids at concentrations that range into the middle to low ppb range. Samples must be in water solutions, not too concentrated, too acidic, or too alkaline.

Routinely analyzed ions

Anion System Cation System
Species Detection limit, ppb  Species  Detection limit, ppb
F- 1 Li+ 1
Cl- 10 Na+ 10
Br- 10* K+ 10
NO2- 10 NH4+ 10
NO3- 10 Mg2+ 20
SO42- 15 Ca2+ 20
PO43- 25 Sr2+ 50
Glycolate 20 Requires additional standards
Acetate 15 Ba2+ 100
Formate 10    
Propionate 25    
Methyl sulfonate 25    
Oxylate 50*    
Requires post-column reagent setup
SiO2(aq) 200    
*Low detection limits only possible in low sulfate samples.


The instrumentation described here was funded in part by the National Science Foundation, grant DUE-9751725, and grants from the Sherman-Fairchild Foundation and the Kresge Foundation.